Heat exchange tubing



Nov. 17, 1931. w. c. s. GRAHAM HEAT EXCHANGE TUBING Filed April 5. 1929 2 Sheets-Sheet l Nov. 17, 1931. w. c. s. GRAHAM HEAT EXCHANGE TUBING Filed April 5. 1929 2 Sheets-Sheet 2 [NVE/v Toe.

Patented Nov. 17, 1931 PATENT OFFICE WARREN O. S. GRAHAM, F NEW ORLEANS, LOUISIANA HEAT EXCHANGE TUBING Application led April 5, 1929. Serial No. 352,712.

My invention relates broadly to an appaf ratus for improving the conduction of heat from hot gases, the products of combustion, or any other source, to a substance inside of a pipe or tubeconveying water, steam, oil, etc.

My invention employs a principle in which the gases ofcombustion are made to circulate around the tubes of my invention and thereby better transfer the heat tothe substance inside the tube and at the same time retard the gases of combustion in order to extract from them the maximum of heat possible.

An object of my invention is to provide .construction of tube by which maximum eiiiciency may be obtained Wherever the tube involving my invention is used or employed,

particularly in connection with economizers,

superheaters, in boilers or steamgenerators,

in a tubing of the boiler or steam generator proper, in water Walls in furnaces or floors,

or in any connection whatsoever therewith.

Another object of my invention is to provide a construction of water tube the outer surface of which is constructed to insure the maximum conduction of heat from the products of combustion circulating around the tube to the fluid circulating through the tube.

Still another object of my invention is to provide a structure of tube for heat generating systems in which a member is integrally connected with the walls of the tube and is so shaped as to pocket or embrace the products of combustion to such an extent that maximum transfer of heat from the surface of the tube to the interior walls of the tube is obtained.

My invention may also be employed to obtain a maximum of eiiiciency in cooling by having the cooling agent, instead of the hot gases or products of combustion, pass over the exterior of the tube involving my invention. This cooling medium or agent may be liquid, air, or any other substance possessing cooling qualities.

4) My invention provides a most etlicient means of transferring heat from hot gases, after these gases have been passed through a boiler or steam generator, to water circulating within the tube of my invention,

o such as is commonly employed in economizers. Hot gases or products of combustion, etc., passing parallel with the tube involving my invention, flow around the spiral ring on the outer surface of the tube and thereby transmit a maximum of heat transfer to the substance inside of the tube. My invention may also be employed to advantage in Waste type boiler installations. 'W hen employed as a superlieater, the hot gases can be so baffled that they will pass the full length of the tube involving my invention and'tliereby take advantage of the maximum amount 0f heat transfer with the minimum amount of loss caused by the slowing up of. the gases.

My invention will be more clearly understood by reference lto the accompanying drawings in which:

Figure l shows my invention applied to a superheater; Fig. 2 illustrates my invention applied to an economizer; Fig. 3 is an enlarged view partially in cross-section of a. water. tube constructed in accordance with my invention; Fig. 4 is an end view showing the water tube illustrated in Fig. 3; Fig. 5 illustrates a modiiiedwform of mounting for the tube structure of my invention with respect to the standard type of boiler and tubing; Fig. 6 shows a modified form of water tube embodying my invention and applied to awwater tube boiler system and showing the path provided for the products of combustion around the tube of my invention; Fig. 7 is an enlarged side elevation showing the form of water tube illustrated in Fig. 6; Yand Fig. 8 is a plan view of the type of water tube Villustrated in Fig. 6.

z This tubing may be either slipped or pressed over the ordinary conventional boiler or steam generator tubing or any special tubing as illustrated in Fig. 5, or it may be made integral therewith forming a part of the tube itself, as shown in the other views. This tubing may be made in sections or it may be employed in single lengths. It can be seen from the drawings that the distance between the rings forming the spiral may be varied, depending upon the service in which the tube is employed and the rate of heat transfer desired. The distance to which these rings protrude from the tube it` self may also be varied and is dependent upon the service in which the tube is em ployed.

The tube of my invention with a spiral ring thereon placed so the gases will pass from one end of the tube to the other, or in the same direction or parallel with the tube it. self, will cause these gases to follow the spiral ring, thereby increasing its efficiency. With the gases passing around the spiral ring the maximum of heat is absorbed on all sides. This likewise applies to the cooling of a substance inside of the tube by passing of a coolinv mixture over the tube.

Ieferring to the drawings in detail, Fig. 1 shows the application of my invention to a superheater in a boiler plant where heat from the furnace 3 is conveyed in the form of heat currents as indicated at 2 over the 'boiler tubes around baille 5, recrossing the v invention disposed vertically between header 8 and 9 to which are connected the inlet and outlet pipes 10 and 11. A multiplicity of tubes are employed, although I have indicated three such. tubes at 12, 14 and 15. Each tube'isl provided with a spirally arranged flange 16, the spiral flange being cupped or pocketed as shown at 18 and terminating in a rounded edge 17 by which the moving gases are made to adhere closely to the exterior walls of the tube.

`In Fig. 5 I have shown the spiralled and flanged tube 12 inserted over the usual boiler tube 30 for providing a heat conducting surface by which the heat may be conveyed by conduction into the inner tube 30, it being unnecessary in this instance to modify the usual boiler tube 30.

-In Fig. 6 I have shown my invention as applied to a water tube boiler which is heated from the furnace hearth 19, the tubes being arranged in sets as represented at 20 and 21 separated by a baille 3l. rlhe spiral flange on the tubes shown in Fig. 6 differs from the corresponding flange on the tube illustrated in Figs. 1 through 5 in that the portions of the spiral are pitched in the manner of a screw with the peripheral edges thereof terminating in relatively flatl extensions. This structure permits the tube to be used either in a cooling` system or a heating system with advantageous results.

By reason of the spirally arranged flange 24 on the tubes which I have-referred to more clearly in Figs. 7 and 8 at 23, the gases are made to follow a course closely adhering to the walls of the boiler tubes, thereby imparting a high degree of heat to the tubes. The spiral formation of continuous flange provides means for establishing a path for products of combustion around the several tubes and insures the heating of the contents of the tubes to the maximum degree.

It will be understood that variations in structure of the tube may be made within the scope of the appended claims without departinfT from the spirit of my invention.

Vhat I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a furnace structure a multiplicity of fluid conducting tubes, each of said tubes having a spirally arranged flange on the exterior walls thereof, means for directing products of combustion over said tubes, the spirally arranged flanges being integrally connected with the walls of said tubes and cupped at the peripheries thereof toward the walls of said tubes to establish a spiral path for heating gases immediately around the exterior walls of said tubes for imparting heat to said walls and the circulating fluid therein.

2. In a furnace structure a multiplicity of parallel fluid circulating tubes, each of said tubes having an integrally formed spiral flange connected to the exterior walls thereof and cupped in the direction of said walls for guiding products of combustion around said tubes in a spiral path immediately adj acent the exterior walls of the tubes for transferring heat to the walls of said tubes and to the fluid contents passing therethrough.

3. In a furnace structure a plurality of parallel fluid circulating tubes, each of said tubes having correspondingly aligned spiralled flanges integrally connected with the exterior walls thereof, said flanges having a concave under surface directed toward the exterior walls of said tubes and disposed to establish a path for moving products of com bustion immediately around said fluid circulating tubes for transferring heat from the exterior to the interior of said fluid circulating tubes.

4. In a water tube boiler, a tubular member constituting a fluid circulating path and a sleeve concentrically disposed about said tubular member, said sleeve carrying an integrally connected spiral flange thereon, said flange being cupped in a direction toward said sleeve to retain a zone of hot gases immediately around the sleeve for transferring heat to the fluid circulating in said tubular member.

5. In a fluid circulatin system, a. tubular member for the passa e o fluid, a. sleeve concentrically disposed a out said tubular member, said sleeve carrying a spirally. disposed integrally connected ange thereon, said flange being substantially cupped to retain products of combustion in Ia heated zone immediately surrounding the sleeve for translerring heat to the Walls of said tubular mem- 6. In a fluid circulating system, a tubular member, a sleeve adapted to telescopically engage said tubular member, a spirally disposed flange integrally connected with the exterior Walls of said sleeve, said flange having its peripheral ed e directed opposite the normal path of flow ger productsof combustion around the sleeve for establishing a zone of heated gases immediately surrounding the sleeve and eilecting a transfer of heat to the fluid passing through said tubular member.

In testimony whereof I aliX my sifrnature.

WARREN c. s. GRAAM. 

